A slide rail assembly includes a first rail, a supporting member, and a second rail movably coupled to the first rail. The first rail defines a first channel. The supporting member includes a pair of supporting portions and a supporting wall that jointly define a supporting channel. The second rail corresponds to the first channel and the supporting channel. The supporting member is movable relative to the first rail from a first position to a second position, such that the second rail is supported by the supporting portions of the supporting member in the course of moving relative to the first rail.